Serum pen



FIG. 1 is a front perspective view of a serum pen.

FIG. 2 is a front elevation view of the serum pen of FIG. 1.

FIG. 3 is a back elevation view of the serum pen of FIG. 1.

FIG. 4 is a left side elevation view of the serum pen of FIG. 1.

FIG. 5 is a right side elevation view of the serum pen of FIG. 1.

FIG. 6 is a top plan view of the serum pen of FIG. 1; and,

FIG. 7 is a bottom plan view of the serum pen of FIG. 1. 

CLAIM We claim the ornamental design for a serum pen, as shown and described. 